Correcting ¹²⁹Xe Gas Exchange MRI for Incidental Gas-Phase Excitation-Comparing Approaches, and Identifying...

Area of Science:

• Medical Imaging
• Biophysics
• Pulmonary Medicine

Background:

• 129Xe MRI gas exchange imaging is crucial for assessing lung function.
• Incidental gas-phase resonance excitation can contaminate dissolved-phase signals.
• This contamination biases measurements of membrane transport and red blood cell (RBC) transfer.

Purpose of the Study:

• To quantify acceptable levels of gas-phase contamination in 129Xe MRI.
• To compare the efficacy of Hahn and Willmering correction frameworks for gas contamination.
• To establish correction protocols for improved accuracy in gas exchange MRI.

Main Methods:

• Healthy volunteers underwent 129Xe MRI with intentionally increased gas contamination.
• Hahn and Willmering correction methods were applied and optimized.
• Correction efficacy was evaluated by comparing corrected metrics against healthy reference thresholds.

Main Results:

• Shortened RF pulses resulted in 24% ± 6% gas contamination.
• Both corrected methods improved RBC signal-to-noise ratio (SNR) by ~9% and reduced noise.
• Gas contamination exceeding ~9% ± 3% led to unacceptable metric deviations.

Conclusions:

• Gas-phase contamination exceeding 9% necessitates correction in 129Xe MRI.
• Both Hahn and Willmering methods provide effective correction after empirical phase calibration.
• These findings enable more accurate quantification of gas exchange parameters.